KR20010029823A - Display Device And Electronic Apparatus Using The Same - Google Patents

Abstract

PURPOSE: To brighten a display, furthermore to reduce parallax in the case of the black and white display and to realize a bright color display in the case of the color display with respect to a reflective display. CONSTITUTION: An upper side polarizing plate 130 is arranged on the upper side of the TN liquid crystal panel 140. A color filter 150, a lower side polarizing plate 160, a light diffusion plate 170, a reflective polarizing plate 180, a backlight 190 and a light reflection plate 200 are successively arranged on its lower side. Then the relation between the haze value (H) of the light diffusion plate 170 and the distance (d) between the light diffusion plate 170 and the light reflection plate 200 is set to satisfy H >= -200d+140. Therefore the incident light 111 on the light reflection plate 200 passing through the light diffusion plate 170 is sufficiently diffused so as to reduce parallax in the black and white display and to make the reflected light white on the color display.

Description

Display Device and Electronic Apparatus Using The Same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device and an electronic device using the same. In particular, the present invention relates to a reflection type liquid crystal display device that reflects external light and displays the light, and a reflection type that reflects external light and displays the light, and a transmission type that transmits light through the light source and displays the light. The present invention relates to a transflective reflective display device and an electronic device using the same.

Background Art Conventionally, display devices using liquid crystal panels include reflective display devices that display using external light, and transmissive display devices that irradiate light from the back of the liquid crystal panel.

In the case of the reflective display device, since the amount of external light decreases in a dark place, it becomes difficult to see the display. On the other hand, in the case of the transmissive display device, the power consumption is increased by the amount of light source regardless of the bright or dark place, and is not particularly suitable for a portable display device operated by a battery.

Thus, there is a semi-transmissive reflective display device that can use both a reflective type and a transmissive type. In this display device, when used in a bright place, the amount of light emitted from the display screen using optical elements such as a liquid crystal and a polarizing plate disposed on the optical path while reflecting external light incident from the display screen on the light reflecting plate formed inside the device. Is controlled for each pixel to perform reflective display.

On the other hand, in the case where the display device is used in a dark place, the light is emitted from the display screen using the above-described optical elements such as a liquid crystal and a polarizing plate while irradiating light source light with a built-in light source such as a backlight on the back side of the liquid crystal panel. Transmissive display is performed by controlling the amount of light for each pixel.

In addition, in a reflective and transmissive display device, a liquid crystal filled in a liquid crystal panel is used to determine whether a liquid crystal is charged by applying a TN (Twisted Nematic) liquid crystal, a STN (Super-Twisted Nematic) liquid crystal, or the like to a pixel. The polarization axis is rotated to make the transmission polarization axis variable.

The polarizing plate transmits light having a linearly polarized light component in a predetermined direction.

Here, the transflective display device according to the prior art will be described with reference to FIG.

In FIG. 10, 5110 is a voltage application region of the TN liquid crystal panel, and 5120 is a voltage non-application region of the TN liquid crystal panel.

5130 is an upper polarizing plate, 5302 is an upper glass plate, 5304 is a lower glass plate, 5160 is a reflective polarizing plate, 5307 is a transflective light absorbing plate, and 5210 is a light source.

First, the case where black-and-white display is performed by the reflective display is described.

The incident light 5601 incident from the outside of the display device becomes light having a linearly polarized light component in a direction parallel to the ground in the upper polarizer 5130, and the polarization direction is almost 90 ° in the voltage-free region 5120 of the TN liquid crystal panel. Light having a linearly polarized light component in a direction perpendicular to the twisted surface, and reflected as light having a linearly polarized light component in a direction perpendicular to the ground in the reflective polarizer 5160, and again in a voltage-free region 5120 of the TN liquid crystal panel. It becomes the light which has a linearly polarized light component parallel to the ground which the polarization direction twisted about 90 degrees, and it exits from the upper polarizing plate 5130. Therefore, when no voltage is applied to the TN liquid crystal panel, white display is obtained.

On the other hand, incident light 5603 incident from the outside of the display device becomes light having a linearly polarized light component in a direction parallel to the ground in the upper polarizer 5130, and does not change the polarization direction in the voltage application region 5110 of the TN liquid crystal panel. And transmitted as light having a linearly polarized light component parallel to the ground, and then absorbed by the semi-transmissive light absorbing plate 5307, whereby black display is obtained.

Next, the case where black-and-white display is performed by transmissive display is described.

The light 5602 from the light source 5210 passes through the opening formed in the transflective light absorbing plate 5307, and becomes light having a linearly polarized light component in a direction parallel to the ground in the reflective polarizer 5160, and is a TN liquid crystal panel. In the voltage-free region 5120, light having a linearly polarized light component perpendicular to a ground plane in which the polarization direction is twisted by approximately 90 ° is absorbed by the upper polarizing plate 5130 and becomes black display.

On the other hand, the light 5604 from the light source 5210 passes through the opening formed in the transflective light absorbing plate 5307, and becomes light having a linearly polarized light component in a direction parallel to the ground in the reflective polarizer 5160, and TN. In the voltage application area 5110 of a liquid crystal panel, it transmits as light which has a linearly polarized light component of the direction parallel to the ground, without changing a polarization direction, and becomes white display.

Generally, in the display apparatus using a liquid crystal panel, the thickness of a liquid crystal layer is very small (about 5 micrometers-10 micrometers). On the other hand, since the substrate thickness is 0.3 mm to 0.7 mm, it is very thick compared to the liquid crystal layer.

Therefore, when reflective display is performed using the above-described conventional display device, as shown in Fig. 11, the optical path in the liquid crystal layer of the external light incident from the upper side of the liquid crystal panel is a moving path and a return path ( There are significant differences in returning paths. Therefore, depending on the incident angle of the external light incident on the liquid crystal panel, the pixel passing the external light in the traveling path and the pixel passing in the return path are different. In the case where the observer sees this optical path difference at an oblique angle, when the monochrome display without a color filter is used, it causes a phenomenon in which the shadow appears on the display, a so-called parallax (parallax). In addition, in a display device using a color filter having a plurality of colors, the color passing through the light path and the return path is different, resulting in a problem of mixed color.

In addition, in the above conventional technology, only the transflective display device is shown, but the problem thereof is a structure in which the transflective light absorbing plate 5307 is replaced with the light absorbing plate except for the light source 5210 from the display device of FIG. 11. The same occurs in the reflective display device.

A first object of the present invention is to provide a reflective or semi-transmissive reflective display device with reduced parallax and mixed color generated during reflective display.

In addition, since the transflective light absorbing plate 5307 is employed in the conventional transflective display device shown in Fig. 10, some or most of the light emitted from the light source 5210 is half when transmissive display is performed. Since the light is absorbed by the transmitted light absorbing plate 5307, the light emitted from the light source 5210 can not be effectively utilized, and there is a problem that the display becomes dark.

A second object of the present invention is to realize a display device capable of effectively utilizing the light emitted from a light source and enabling bright transmissive display.

In addition, in the display device using the reflective polarizer, on the basis of the above display principle, positive display is performed at the time of reflective display and negative display at the time of transmissive display, so-called positive negative inversion occurs.

A third object of the present invention is to prevent this positive negative inversion in a semi-transmissive reflective display device using a reflective polarizer.

In order to achieve the above object, a display device of the present invention includes a liquid crystal panel formed by inserting a liquid crystal between substrates, first polarizing means provided on one side of the liquid crystal panel, and light formed on the other side of the liquid crystal panel. A display device having reflecting means and light diffusing means disposed between the liquid crystal panel and the light reflecting means, wherein the light diffusing means has a forward scattering characteristic, and the distance between the light diffusing means and the light reflecting means When d is (mm), the haze value H (%) of the light diffusing means satisfies the relationship of H≥-200d + 140.

According to the display device of the present invention, the external light incident from the upper side of the liquid crystal panel is sufficiently diffused by the light diffusing means having the forward scattering characteristics, and then reflected by the light reflecting means provided at a predetermined distance away from the light diffusing means. Subsequently, light is diffused sufficiently by the light diffusing means to irradiate the liquid crystal panel from the back side. Therefore, even when external light enters the liquid crystal panel at an arbitrary angle of incidence, parallax does not occur because the light reflected by the light reflecting means and irradiated from the back side of the liquid crystal is sufficiently diffused light.

Furthermore, in one aspect of the present invention, a color filter is formed between the first polarizing means and the light diffusing means, and the color filter includes a plurality of colored layers.

According to the display device of this aspect, the external light incident on the liquid crystal panel is once colored in a plurality of colors by a color filter, but then the plurality of colors sufficiently diffused by the light diffusing means having forward scattering characteristics are mixed with each other. . And it reflects by light reflection means, and irradiates a liquid crystal panel from the back side. Since the light irradiating this liquid crystal panel from the back side is light close to white mixed with a plurality of colors, even if external light enters the liquid crystal panel at an arbitrary angle of incidence, no mixed color occurs.

Moreover, in another aspect of this invention, the said color filter has red, green, and blue colored layers, It is characterized by the above-mentioned.

According to the display device of this aspect, the external light incident on the liquid crystal panel is colored in a plurality of colors by a color filter having red, green and blue colored layers, and then diffused by the light diffusing means. At that time, since red, blue, and rust are mixed with each other, the diffused light becomes extremely white. And since the white light is irradiated from the back side by the liquid crystal panel, the display excellent in color balance can be obtained.

Moreover, in another aspect of this invention, the 2nd polarizing means which isolates incident light according to the polarization component is provided between the said liquid crystal panel and the said light reflection means, It is characterized by the above-mentioned.

According to the display device of this aspect, contrast display is performed by polarizing separation of the external light transmitted through the liquid crystal panel by the second polarization means.

As the second polarizing means, it is preferable to employ polarizing means that transmits most of the light of the first linearly polarized light component and absorbs most of the light of the second linearly polarized light component that is substantially orthogonal to the one linearly polarized light component.

By adopting such a polarizing means, dark display can be performed by absorbing the external light transmitted through the liquid crystal panel by the second polarizing means, and bright display can be performed by transmitting the second polarizing means and then reflecting it. As a result, a reflective display with excellent contrast characteristics is realized.

According to another aspect of the present invention, there is also provided a lighting device having a transparent light guide and a light source capable of introducing light into the light guide, wherein the lighting device is disposed between the light diffusing means and the light reflecting means. It features.

The display device according to the present aspect relates to a so-called transflective display device capable of performing transmissive display by light source light when it is dark and reflecting display by external light when light. According to the display device of this aspect, a transflective display device capable of reflective display without parallax or mixed color is realized. Moreover, even in the transmissive display, since the light emitted from the light source is sufficiently diffused by the light diffusing means having the forward scattering characteristics, there is also an effect that light can be uniformly irradiated onto the liquid crystal panel. In addition, since the distance between the light scattering means and the light reflecting means is separated according to the thickness of the light guide, the above-described separation dimension d is secured.

According to another aspect of the present invention, there is provided a second polarization means for separating incident light according to the polarization component between the liquid crystal panel and the illumination device, and is provided between the second polarization means and the illumination device. And a reflective polarizer that transmits light substantially of the first linearly polarized light component and reflects light of the second linearly polarized light component substantially perpendicular to the one linearly polarized light component, and has a transmission axis of the reflective polarizer and the second polarized light. It is characterized in that the transmission axis of the means is substantially coincident.

According to the display device according to this aspect, light in the polarization direction, such as the transmission axis direction of the reflective polarizer, of the light emitted from the illumination device transmits the reflective polarizer. On the other hand, light in the polarization direction, such as the reflection axis of the reflective polarizer, is reflected by the reflective polarizer. The light is reflected by the light reflecting means and returns to the reflective polarizer again. And while this reflection is repeated, anything passes through the reflective polarizer. That is, most of the light emitted from the illumination device is emitted toward the second polarization means as light in the polarization direction such as the transmission axis direction of the reflective polarizer. And this light is transmitted toward the liquid crystal panel through the second polarization means in which the transmission axis of the reflective polarizer and the transmission axis are set in parallel. Therefore, a bright transmissive display excellent in utilization efficiency of the light emitted from the illuminating device is realized. In addition, since the transmission axis of the reflective polarizer and the transmission axis of the second polarizing means coincide, no adverse influence is given to the external light incident from the upper side of the liquid crystal panel, and thus so-called positive negative inversion does not occur.

In addition, the electronic device of the present invention includes a liquid crystal panel formed by inserting a liquid crystal between substrates, first polarizing means provided on one side of the liquid crystal panel and separating incident light according to its polarization component, and An electronic apparatus comprising a display device having light reflecting means provided on the other side and light diffusing means disposed between the liquid crystal panel and the light reflecting means, wherein the light diffusing means has a forward scattering characteristic, When the distance between the light diffusing means and the light reflecting means is set to d (mm), the haze value (H) (%) of the light diffusing means satisfies the relationship of H≥-200 d + 140. It features.

According to the electronic device of the present invention, an electronic device without parallax or color mixing is realized.

1 is a perspective view illustrating a reflective polarizer used in a display device according to the present invention.

2 is an explanatory diagram showing a reflective display principle according to the present invention;

3 is an explanatory diagram showing a transmissive display principle according to the present invention;

4 is an explanatory diagram showing a measurement experiment of parallax;

5 is a schematic configuration diagram showing a display device according to the first embodiment.

6 is a schematic block diagram showing a display device according to a second embodiment.

7 is a schematic configuration diagram showing a display device according to a third embodiment.

8 is a schematic block diagram showing a display device according to a fourth embodiment.

9 is a schematic configuration diagram showing a display device according to a fifth embodiment.

10 is a schematic configuration diagram showing a display device according to the prior art.

11 is an explanatory diagram showing a state in which parallax is generated in a display device according to the prior art;

Explanation of symbols on the main parts of the drawings

10; Display devices 12 and 130; Upper polarizer

15, 160; Lower polarizer 20; STN cell (liquid crystal panel)

26; Liquid crystal 27, 150; Color filter

30, 170; Light diffuser plates 40 and 180; Reflective polarizer

70; Light sources 80 and 200; Light reflector

140; TN liquid crystal panel 190; Backlight

Next, the display principle of the display device concerning this invention is demonstrated in detail, referring FIG. 2, FIG. Incidentally, the transflective display device is exemplified below, but the display principle of reflection does not change even in the reflective display device.

The liquid crystal display device uses a TN liquid crystal panel 140 as a transmission polarization axis variable optical element. In addition, an upper polarizer 130 is installed above the TN liquid crystal panel 140, and a color filter 150 and a lower polarizer 160 formed of RGB (red, green, blue) below the TN liquid crystal panel 140. ), The light diffusion plate 170 and the reflective polarizing plate 180 are provided in this order. In addition, the backlight 190 and the light reflector 200 serving as light sources are sequentially provided below the reflective polarizer 180.

The transmission axis of the upper polarizer 130 and the transmission axis of the lower polarizer 160 are substantially orthogonal, and the transmission axis of the lower polarizer 160 and the transmission axis of the reflective polarizer 180 are in parallel with each other. In addition, the light diffusion plate 170 performs forward scattering having a haze value (H).

In addition, 141 on the left side represents a voltage-free region in which no voltage is applied to the TN liquid crystal panel 140, and 142 on the right side represents a voltage application region in which voltage is applied.

The display device configured in this manner will be described next with reference to FIG. 2 for the operation of the reflective display.

First, the case where light incident from the outside passes through the voltage-free region 141 of the TN liquid crystal panel 140 will be described.

The incident light 111 incident from the outside of the display device is transmitted only by light having a linearly polarized light component in a direction parallel to the ground by the upper polarizer 130, and then the light is not applied to the voltage-free region of the TN liquid crystal panel 140. Light having a linearly polarized light component in a direction perpendicular to the ground where the polarization direction is twisted by approximately 90 ° by 141 results in the color filter 150, the lower polarizer 160, the light diffuser plate 170, and the reflective polarizer 180. ) Is transmitted as a linearly polarized light component in a direction perpendicular to the ground, passes through the transparent backlight 190 and reaches and reflects the light reflecting plate 200. Of the light reflected by the light reflecting plate 200, only the light 112 having the linearly polarized light component in the direction perpendicular to the ground is again the backlight 190, the reflecting polarizing plate 180, the light diffusing plate 170, and the lower polarizing plate ( 160, light passing through the color filter 150 and having a linearly polarized light component in a direction parallel to the ground plane of the polarization direction is substantially 90 ° by the voltage-free region 141, and the light is emitted light 113. It is emitted as).

The light reflected by the light reflector 200 includes not only light 112 having a linear polarization component in a direction perpendicular to the ground, but also light 114 having a linear polarization component in a direction parallel to the ground. For this reason, this light 114 is reflected by the reflective polarizing plate 180, is reflected by the light reflecting plate 200 again, the polarization direction is changed, and the light 115 which has a linear polarization component of the direction perpendicular | vertical to the ground partly ) To pass through the reflective polarizer 180. By repeating this, light can be effectively used, and the light emitted from the upper polarizing plate 130 can be made approximately 1.6 times brighter than the case where the reflective polarizing plate 180 is not used.

Here, although the incident light 111 and the outgoing light 113 appear to pass through the color filters 150 having different colors, the light diffusion plate 170 is provided between the lower polarizer 160 and the reflective polarizer 180. Therefore, when passing through the light diffusion plate 170, the light passing through the color filter 150 of each color is diffused. For this reason, red, green, and blue are mixed with light reflected by the light reflecting plate 200 so that a specific color is not strongly colored. As a result, the light 113 emitted from the upper polarizing plate 130 is colored with the color of the color filter 150 through which the light reflected by the light reflecting plate 200 passes.

Next, a case where light incident from the outside passes through the voltage application region 142 of the TN liquid crystal panel 140 will be described.

Of the incident light 116 incident from the outside of the display device, only light having a linearly polarized light component in a direction parallel to the ground is transmitted by the upper polarizing plate 130, and then the light is applied with a voltage of the TN liquid crystal panel 140. It passes through the region 142 without changing the polarization direction, passes through the color filter 150, and is absorbed by the lower polarizing plate 160 to become dark.

As described above, in the voltage-free region 141, the light incident on the display device by the reflective polarizer 180 can be effectively used, and the light reflected by the light reflector 200 is colored by the color filter 150. One light exits 113 and is emitted. On the other hand, in the voltage application region 142, light is absorbed by the lower polarizing plate 160 and becomes dark.

Next, the operation of the transmissive display will be described with reference to FIG. 3.

First, the case where the light emitted from the backlight 190 passes through the voltage free region 141 of the TN liquid crystal panel 140 will be described.

Of the light source light generated from the backlight 190, the light 121 having the linearly polarized light component in the direction perpendicular to the ground is the reflective polarizer 180, the light diffuser 170, the lower polarizer 160, and the color filter 150. ), And the voltage-free region 141 of the TN liquid crystal panel 140 becomes light having a linearly polarized light component in a direction parallel to the ground twisted about 90 °, and the light is the upper polarizing plate 130. Is emitted as the outgoing light 122 from the.

The light source light from the backlight 190 includes not only the light 121 having the linear polarization component in the direction perpendicular to the ground but also the light 123 having the linear polarization component in the direction parallel to the ground. Accordingly, the light 123 is reflected by the reflective polarizer 180, the light is reflected by the optical reflector 200, and the polarization direction is changed, and the light 124 having a linear polarization component in a direction perpendicular to the ground is partially And passes through the reflective polarizer 180. By repeating this, the light can be effectively used, and the emitted light 122 can be made bright.

Next, the case where the light source light from the backlight 190 passes through the voltage application region 142 of the TN liquid crystal panel 140 will be described.

Among the light sources of the backlight 190, the light 125 having the linearly polarized light component in a direction perpendicular to the ground is formed by the reflective polarizer 180, the light diffuser 170, the lower polarizer 160, and the color filter 150. After passing through the light, the light passes through the voltage application region 142 of the TN liquid crystal panel 140 without changing the polarization direction. The light is absorbed by the upper polarizer 130 and darkened.

In addition, among the light source light from the backlight 190, the light 126 having the linearly polarized light component in a direction parallel to the ground is reflected by the reflective polarizer 180, is reflected by the light reflector 200, and the polarization direction is changed. Part of the light 127 having a linear polarization component in a direction perpendicular to the ground, and passes through the reflective polarizer 180. However, this light 127 also passes through the voltage application region 142 of the TN liquid crystal panel 140 without changing the polarization direction, and is absorbed by the upper polarizing plate 130 to become dark.

In this manner, by the combination of voltage application and no application of the TN liquid crystal panel 140, the emitted light 113 and 122 colored by the color filter 150 is emitted.

Furthermore, in the display device according to the present invention, since the light diffusion plate 170 and the light reflection plate 200 are provided, as in the incident light 111 shown in FIG. 2, the display device has a linearly polarized light component in a direction parallel to the ground. The light passes through the red color of the color filter 150, for example, and is colored red to pass through the lower polarizer 160, the light diffuser 170, the reflective polarizer 180, and the backlight 190, and the light reflector 200. ) Since the red light is scattered forward when passing through the light diffusion plate 170, the light reaching the light reflection plate 200 not only passes through the red color filter 150 but also green and blue light. The light which received the color of green and blue which passed through mixes with each other, and approaches to white light. For this reason, although the light 112 reflected by the light reflection plate 200 is considered to be red in FIG. 2, the light subjected to the coloring of other colors (green and blue) diffused from the light diffusion plate 160 is substantially the same. Because of the reflection, the reflected light becomes white. In addition, the white light passes through the backlight 190, the reflective polarizer 180, the light diffuser 170, and the lower polarizer 160, and passes through a specific color (eg, green) of the color filter 150. The light emitted through the liquid crystal panel 140 and the upper polarizer 130 is colored rust.

In addition, the present inventors conducted a sharp experiment in order to reduce parallax (lag) which arises when black-and-white display is performed by reflective display in the display apparatus by the said structure. In this experimental method, as shown in FIG. 4, after tilting the display device by 30 degrees, incident light is incident from a direction inclined at 45 degrees with respect to the display device, and the observer observes parallax directly from above. The experimental result of 1 was obtained. In Table 1, the haze value H is a diffusion ratio (5 to 95%) of the light diffusion plate 170, and the separation dimension d is the separation dimension (mm) of the light diffusion plate 170 and the light reflection plate 200. Are respectively shown.

0.7 0.6 0.5 0.4 0.3 0.2 Haze value (H) 15 △ × × × × × 24 ○ △ × × × × 47 ○ ○ ○ × × × 82 ◎ ○ ○ ○ △ × 95 ◎ ○ ○ ○ ○ ×

However, in Table 1 ◎: The shadow is faint and the display is easy to understand

○: The shadow is faint

(Triangle | delta): The shadow is a little prominent.

×: the shadow is clearly

In addition, when the relationship between the haze value H by Table 1, and the space | interval dimension d is represented by Formula, it becomes as following Formula 1.

H≥-200d + 140

Thus, the display device is configured to satisfy the equation (1).

As a result, the light diffuser plate 170 may contact the light reflector 200 in a state in which the light emitted from the light diffuser plate 170 is sufficiently diffused, and the generation of parallax may be reduced.

On the other hand, in the case of performing color display by the reflective display, the incident light is colored when passing through the color filter 150 and reflected by the light reflecting plate 200 in an insufficient diffusion state by the light diffusing plate 170. In this case, the light incident on the TN liquid crystal panel 140 is mixed with the pre-colored color as the primary color, resulting in a color uneven display.

Therefore, by setting the display device so as to satisfy the above expression (1), it is possible to bring the light colored in red, green, and blue to reach the light reflection plate 200 into a state in which the light is sufficiently diffused. For this reason, the light reflected by the light reflection plate 200 can be made into white light which mixed red, green, and blue uniformly. As a result, by making the light irradiated from the back side of the liquid crystal panel 140 at the time of reflective display into white, clear color display without color unevenness can be realized.

If the color filter 150 is a dot matrix display composed of red, green, and blue, multi-color display and full-color display can be performed.

In the above description, the white mode is normally described, but the normal black mode is also possible. In addition, in the normal white mode, in either of the reflective display and the transmissive display, the display is brightened by the reflective polarizing plate 180 and the light reflecting plate 200.

In the above configuration, the TN liquid crystal panel 140 has been described as an example. However, in place of the TN liquid crystal panel 140, another transmission polarization axis such as an STN liquid crystal panel or an electrically controlled controlled liquid crystal panel (ECB) liquid crystal panel is converted by voltage or the like. Even if it is used, the basic operation principle is the same.

In addition, in the display device, the reflective polarizer 180 is provided between the light diffusion plate 170 and the backlight 190 to brighten the emission light 113 and 122, but the reflective polarizer 180 is omitted. You may also

It is also possible to configure the reflective display device in which the backlight 190 is omitted.

Next, with reference to FIGS. 1-3, the principle of a reflective polarizing plate is demonstrated. 1 is a schematic perspective view of a reflective polarizing plate serving as a reflective polarizing means, and FIGS. 2 and 3 are schematic views of a display device using a reflective polarizing plate.

First, the structure of the reflective polarizing plate 180 will be described with reference to FIG. 1. The reflective polarizing plate 180 has a laminate structure in which two different layers {1 (A layer) and 2 (B layer)} are alternately stacked. Here, in the layers 1 and 2, unlike the refractive index nAX in the X direction and the refractive index nAY in the Y direction of the A layer 1, the refractive index nAY and the B layer in the Y direction of the A layer 1 are different. The refractive index nBY in the Y direction of (2) is formed to be substantially the same.

Therefore, the light having the linearly polarized light component in the Y direction among the light incident on the reflective polarizer 180 from the direction perpendicular to the upper surface 5 of the reflective polarizer 180 passes through the reflective polarizer 180 (6). ) Is emitted as light having a linearly polarized light component in the Y direction. On the contrary, among the light incident on the reflective polarizer 180 from the direction perpendicular to the lower surface 6 of the reflective polarizer 180, light having a linear polarization component in the Y direction passes through the reflective polarizer 180 and the upper surface 5. ) Is emitted as light having a linearly polarized light component in the Y direction. Here, the direction (Y direction) through which light transmits is called a transmission axis.

On the other hand, when the thickness in the Z direction of the A layer 1 is tA, the thickness in the Z direction of the B layer 2 is tB, and the wavelength of the incident light is λ,

tA nAX + tB nBX = λ / 2

The reflective polarizer 180 is formed to satisfy the following.

Accordingly, the light having the linearly polarized light component in the X direction among the light having the wavelength λ incident on the reflective polarizer 180 from the direction perpendicular to the upper surface 5 of the reflective polarizer 180 is the reflective polarizer 180. Is reflected by. The light having the linearly polarized light component in the X direction among the light incident on the reflective polarizer 180 from the direction perpendicular to the lower surface 6 of the reflective polarizer 180 is reflected by the reflective polarizer 180. Here, the direction (X direction) which light reflects is called a reflection axis.

In addition, the reflective polarizer 180 may vary the thickness tA in the Z direction of the A layer 1 and the thickness tB in the Z direction of the B layer 2 so as to cover the entire wavelength range of visible light. By establishing 2, the light having the linearly polarized light in the X direction is reflected by the light having the linearly polarized light in the X direction over all the white light as well as the single color, and the light having the linearly polarized light in the Y direction is reflected by the light having the linearly polarized light in the Y direction. Is transmitted through.

As the layer A of the reflective polarizing plate 180, for example, polyethylene naphthalate (PEN) is used, and in layer B, a copolyester of naphthalene dicarboxylic acid and terephthalic acid (coPEN; copolyester of naphthalene dicarboxylic acid and terephthalic or isothalic acid). In addition, the material of the reflective polarizing plate 180 used for this invention is not limited to this, The material can be selected suitably. In addition, such a reflective polarizing plate is disclosed as a reflective polarizer for example in Japanese Patent Laid-Open No. 9-506985.

(Example)

Next, an embodiment according to the present invention will be described with reference to the drawings.

Example

<First Embodiment>

5 is a schematic structural diagram of a color display device 10 according to the first embodiment. The display device 10 uses the STN cell 20 as the transmission polarization axis variable means. In addition, the retardation film 14 and the upper polarizing plate 12 are sequentially provided on the upper side of the STN cell 20, and the light diffusion plate 30 and the lower polarizing plate 15 are sequentially lowering on the lower side of the STN cell 20. It is installed. In addition, below the lower polarizing plate 15, the reflective polarizing plate 40, the light source 70, and the light reflecting plate 80 are provided in order.

Here, the light source 70 emits light upward with the light guide 72 using the LED (Light Emitting Diode) 71. The light guide 72 is formed with an inorganic transparent material such as an acrylic resin, a polycarbonate resin, an amorphous polyolefin resin, an inorganic transparent material such as glass, or a composite thereof, and has a thickness of about 0.3 mm to 2 mm. Further, a plurality of small protrusions are formed on the surface of the light guide 72, and the size of each of the protrusions is about 380 nm to 700 nm in wavelength of visible light. 300 micrometers or more are suitable for the magnitude | size which is needed and a processus | protrusion is inconspicuous by visual observation.

The light reflecting plate 80 is formed by depositing aluminum or silver on a PET film, or using an aluminum foil.

Moreover, the STN cell 20 comprises the liquid crystal panel by sealing the STN liquid crystal 26 in the cell which consists of two glass substrates 21 and 22 and the sealing member 23. As shown in FIG. Moreover, the transparent electrode 24 is formed in the lower surface of the glass substrate 21, The transparent electrode 25 is provided in the upper surface of the glass substrate 22, and comprises the dot matrix. The transparent electrodes 24 and 25 are made of indium tin oxide (ITO), tin oxide, or the like. Moreover, the color filter 27 which consists of red 27R, green 27G, blue 27B is formed in the lower surface of the transparent electrode 24, and coincides with the electrode pattern of the transparent electrode 25. As shown in FIG. In addition, the color filter 27 may be formed between the glass substrate 21 and the transparent electrode 24 instead of the lower surface of the transparent electrode 24.

The retardation film 14 is used as an optically anisotropic body for color compensation, and corrects the coloring generated in the STN cell 20 to enable monochrome display.

In addition, the reflective polarizing plate 40 in this embodiment uses the reflective polarizing plate 180 described with reference to FIG. 1, and the direction of the transmission axis of the reflective polarizing plate 40 and the transmission axis direction of the lower polarizing plate 15 are Almost coincident.

In addition, the display device 10 according to the present embodiment is set to satisfy the above expression (2). In the display device 10, the haze value H of the light diffusion plate 30 is set to 82%, for example, so as to satisfy the above equation (1), and the separation dimension between the light diffusion plate 30 and the light reflection plate 80. (d) is 0.7 mm, for example.

Next, the operation of the display device 10 according to the present embodiment will be described.

First, in the voltage-free region of the STN cell 20 in the reflective display, light incident from the outside becomes light having a linearly polarized light component in a predetermined direction by the upper polarizing plate 12, and then the STN cell 20 By this, the polarization direction becomes light having a linearly polarized light component having a predetermined angle twisted therethrough, and passes through the light diffuser plate 30, the lower polarizer plate 15, and the reflective polarizer plate 40, and further passes through the light guide 72 to the light reflector plate. Reflected at 80. The reflected light passes through the light guide 72, the reflective polarizer 40, the lower polarizer 15, and the light diffuser 30 again, and the linear polarization component of which the polarization direction is twisted by a predetermined angle by the STN cell 20 is obtained. Light to be emitted is emitted from the upper polarizing plate 12.

In addition, even if the polarization direction is changed among the light reflected by the light reflecting plate 80, the reflection is repeated between the reflecting polarizing plate 40 and the light reflecting plate 80, and immediately from the reflecting polarizing plate 40 to the STN cell 20. Since it is injected toward the surface, a bright display can be obtained. In that case, when the reflected light passes through the color filter 27, the said light can be colored by any color of red, green, and blue.

In addition, in the voltage application region of the STN cell 20, light incident from the outside becomes light having a linear polarization component in a predetermined direction by the upper polarizer 12, and then the STN cell 20 has a linear polarization component. Passed as light, it is absorbed by the lower polarizing plate 15 and becomes dark.

Next, in the voltage-free region of the STN cell 20 in the transmissive display, the light emitted from the light source 70 becomes light having a linearly polarized light component in a predetermined direction by the reflective polarizer 40, and is transmitted therethrough. By 20, the polarization direction becomes light having a linearly polarized light component with a predetermined angle twisted, and is emitted through the upper polarizing plate 12. At this time, the emitted light is colored with the color of the color filter 27 passing through.

On the other hand, in the voltage application region of the STN cell 20, the light emitted from the light source 70 becomes light having a linearly polarized light component in a predetermined direction by the reflective polarizing plate 40, and passes through the STN cell 20. It passes as light having a polarization component, is absorbed by the upper polarizing plate 12, and becomes dark.

As described above, in the display device 10 according to the present embodiment, bright color display can be realized by the color filter 27 having three colors of red, green, and blue in both the reflective display and the transmissive display.

In addition, as the display device 10 according to the present embodiment, the relationship between the diffusion ratio (haze value H) of the light diffusion plate 30 and the spaced dimension d of the light diffusion plate 30 and the light reflection plate 80 is shown. Is formed to satisfy the above equation (1). As a result, the light diffuser plate 30 uniformly contacts the light reflector plate 80 while the light diffuser plate 30 sufficiently diffuses the light colored in the red, green, and blue colors by the color filter 27. The light reflected by the light reflecting plate 80 can be made white light which mixed red, green, and blue.

For example, the light colored in red when the light passes through the enemy 27R of the color filter 27 reaches the light reflecting plate 80 while being sufficiently diffused in the light diffusing plate 30. In addition, the light colored in green when passing through the rust 27G of the color filter 27 reaches the light reflecting plate 80 in a state that is sufficiently diffused by the light diffusing plate 30. In addition, the light colored in blue when passing through the blue 27B of the color filter 27 reaches the light reflecting plate 80 in a state where it is sufficiently diffused by the light diffusing plate 30. Here, in the light reflecting plate 80, these three colors of light are uniformly mixed white light, reflected, and passed through the reflective polarizing plate 40, the optical polarizing plate 30, and the lower polarizing plate 15 to enter the STN cell 20. do. At this time, since the light incident on the STN cell 20 is white when reflected by the light reflecting plate 80, the light emitted from the display device 10 is only in the color of the color filter 27 passing therethrough. It is colored.

As a result, by making the light irradiated from the back side of the liquid crystal panel 140 at the time of a reflective display into white light, it becomes a color unevenness and can prevent color display, and can realize a vivid color display.

<2nd Example>

6 is a schematic diagram of a display device for performing monochrome display according to the second embodiment. That is, in the display device 10, the STN cell 20 ′ having no color filter 27 is used in place of the STN cell 20 having the color filter 27. Further, the lower polarizing plate 15, the light diffusing plate 30, the reflective polarizing plate 40, the light source 70, and the light reflecting plate 80 are sequentially formed below the STN cell 20 ′.

In the display device 10 according to the second embodiment configured as described above, like the display device 10 according to the first embodiment described above, light is sequentially transmitted between the reflective polarizing plate 40 and the light reflecting plate 80. Is reflected so that only light having a linearly polarized light component in a predetermined direction is irradiated from the reflective polarizer 40 toward the STN cell 20 '. This makes it possible to brighten the screen in the reflective display.

In addition, the light diffusion is designed by satisfying the above formula (1) by designing a relationship between the haze value H of the light diffusion plate 30 and the separation dimension d of the light diffusion plate 30 and the light reflection plate 80. When the light irradiated from the plate 30 toward the light reflecting plate 80 reaches the light reflecting plate 80, it can be in a sufficiently diffused state, and the parallax generated during black and white display is reduced to make the screen display clear. can do.

<Third embodiment>

7 is a schematic diagram of a display device according to a third embodiment. In this embodiment, in the display device 10 according to the first embodiment, the positions of the lower polarizing plate 15 and the light diffusion plate 30 are changed, and the lower polarizing plate 15 and the light below the STN cell 20 are changed. The diffusion plate 30 is arranged one by one.

<Fourth Example>

8 is a schematic diagram of a display device according to a fourth embodiment. In this embodiment, in the display device 10 according to the third embodiment, the reflective polarizing plate 40 is disposed between the lower polarizing plate 15 and the light diffusion plate 30, and is disposed below the STN cell 20. The polarizing plate 15, the light reflecting plate 40, and the light diffusing plate 30 are arranged in this order.

<Fifth Embodiment>

9 is a schematic diagram of a display device according to a fifth embodiment. In this embodiment, the lower polarizing plate 15 is omitted in the display device according to the fourth embodiment. As described above, in the display device according to the present embodiment, the display can be made bright by reducing the number of members through which light passes.

2. Modification

In each of the above embodiments, the STN cell 20 is described as an example in the liquid crystal panel. However, the present invention is not limited thereto, and the transmission polarization axis may be changed by a voltage or the like in addition to the TN liquid crystal panel and the ECB liquid crystal panel.

Incidentally, although the third to sixth embodiments have been described with respect to the color display device, it is of course possible to use the display device for performing the black and white display described in the second embodiment.

In addition, the display apparatus 10 mentioned above is a personal computer, a pager, a liquid crystal television, a viewfinder type, a monitor direct view video tape recorder, a car navigation apparatus, an electronic notebook, an electronic calculator, a word processor, a workstation, a mobile telephone, a television. Applicable to electronic devices of devices equipped with telephones, POS terminals, and touch panels.

As described above, in the display device according to the present invention, since the relationship between the haze value H of the light diffusing means and the separation dimension d of the light diffusing means and the light reflecting means is set to H≥-200d + 140, the reflection When monochrome display is performed using the type display, the light reflecting means can be reached in a state where the light emitted from the light diffusing means toward the light reflecting means is sufficiently diffused, and the parallax can be reduced after the display is made bright. .

In the case of color display, the light reflecting means can be reached in a state in which the incident light colored in red, green, and blue is sufficiently diffused, and the light reflecting means reflects these light as white light mixed uniformly and is clear. Color display can be realized.

Claims (8)

A liquid crystal panel formed by inserting a liquid crystal between substrates, first polarizing means provided on one side of said liquid crystal panel, light reflecting means provided on the other side of said liquid crystal panel, said liquid crystal panel and said light reflecting means A display device having light diffusing means disposed between The light diffusing means has a forward scattering property, In the case where the distance between the light diffusing means and the light reflecting means is d (mm), the haze value (H) (%) of the light diffusing means satisfies the relationship of H≥-200d + 140. Display device. The display device according to claim 1, wherein a color filter is provided between the first polarizing means and the light reflecting means, and the color filter includes a plurality of colored layers. The display device of claim 2, wherein the color filter has red, green, and blue colored layers. The display device according to any one of claims 1 to 3, wherein second polarizing means is provided between the liquid crystal panel and the light diffusing means for separating incident light according to the polarization component. The display as claimed in claim 4, wherein the second polarizing means transmits most of the light of the first linearly polarized light component, and absorbs most of the light of the second linearly polarized light component substantially orthogonal to the one of the linearly polarized light components. Device. 4. An illuminating device according to any one of claims 1 to 3, further comprising an illuminating device having a translucent light guide and a light source capable of introducing light into the light guide, wherein the illuminating device is provided between the light diffusing means and the light reflecting means. And a display device. 7. The liquid crystal panel according to claim 6, wherein second polarizing means is provided between the liquid crystal panel and the lighting device to separate incident light according to the polarization component. A reflective polarizer disposed between the second polarizing means and the illumination device and transmitting most of the light of the first linearly polarized light component and reflecting most of the light of the second linearly polarized light component substantially perpendicular to the one linearly polarized light component; , A transmission device in which the transmission axis of the reflective polarizer and the transmission axis of the second polarization means substantially coincide with each other. A liquid crystal panel formed by inserting a liquid crystal between substrates, first polarizing means provided on one side of the liquid crystal panel and separating incident light according to its polarization component, and light reflection provided on the other side of the liquid crystal panel An electronic apparatus comprising a display device having means and light diffusing means disposed between the liquid crystal panel and the light reflecting means, The light diffusing means has a forward scattering property, In the case where the distance between the light diffusing means and the light reflecting means is d (mm), the haze value (H) (%) of the light diffusing means satisfies the relationship of H≥-200d + 140. Electronic devices.